Ground-Breaking Wellington pest trap business Good Nature has started to sell to the general public, but it is already knocking off a range of critters around the world, from mink in Finland, mongoose in Hawaii and feral cats in Australia.

Judging by the rate at which the automated traps were selling, there was a high demand for them, said company co-founder and marketing manager Stu Barr.

The gas powered traps, which are capable of killing multiple rats, mice, stoats and possums, are sold in 53 CRT Farmlands and hunting stores.

The company also sells its products to conservation managers in Australia, Hawaii, South-east Asia, the United Kingdom and Finland.

"We are making about 350 traps a week. Our capacity maxes out at about 600 so we have plenty of capacity left - if we exceeded that it would be a good problem to have," Barr said.

There are two traps - one for possums which will kill 12 possums using one gas cylinder, and another for smaller prey such as rats, mice and stoats which will kill 24 animals per cylinder.

Basic price for the traps is $169, but for another $20 a consumer can buy extra lure and three more gas cylinders. Over time the strength of the lure diminishes and it needs to be replaced.

From a small premise in Kilbirnie, Good Nature employs 12 fulltime staff. Four work in research and development, the remainder in marketing and production.

Barr said much of the demand came from people in rural areas.

"The stories that keep coming back are about catastrophic damage, so a rat might chew through the wiring of a rotary milking shed and you can't milk for a day - imagine what that costs. We also hear of people losing feed, feed being spoiled which you can't use any more, value added goods which have been stored and eaten. And people just don't like rats and mice," he said.

The trap works when a pest, attracted by a lure, sets off a trigger that in turn activates a gas-propelled bolt and kills the animal instantly. It then resets itself ready for the next pest.

Barr said with most traps, the stronger the mechanism killing the animal, the stronger the trigger required. By contrast, the Good Nature trap needed just 20gm of force to set off a 30kg impact, which would kill any pest.

He said the company guarded against imitators by investing heavily in R&D.

"People who copy our traps are copying old technology. The way we will keep ahead is to upgrade constantly," Barr said.

Compared to poison, the traps were more humane as it takes between three and 20 days for poison to work. Rats can die behind walls or under floors, forcing owners to tear their house apart to get rid of the smelly offender.

Started in 2005 by industrial design graduates from Victoria University, Good Nature got off the ground thanks to the Department of Conservation Innovation Fund.

"It was developed solely for the conservation market, but of course protecting your property against rats and possums is the same as protecting a rare population of kiwi - killing the animal is exactly the same, so then we started making this trap available for everyone," Barr said.

In Hawaii the traps are used to kill the introduced mongoose, which eats native birds and snails. Australia is trialling them for feral cat control, in Finland they are being deployed against an introduced mink which has become a pest, and in the UK they are controlling the introduced grey squirrel.